Preparation method, mold and product of ultra-high molecular weight polyethylene nanocomposite material

Abstract

The present invention discloses a method for preparing an ultra-high molecular weight polyethylene nanocomposite product, which includes the steps of: S1: preparing an ultra-high molecular weight polyethylene base material into an ultra-high molecular weight polyethylene melt and injecting it into a mold; S2: cooling the ultra-high molecular weight polyethylene melt to a first temperature under a preset pressure; S3: injecting a low molecular weight polyolefin nanocomposite melt into the ultra-high molecular weight polyethylene melt at a second temperature; and S4: cooling and molding to prepare the ultra-high molecular weight polyethylene nanocomposite product. The present invention ensures the mechanical performance and wear resistance of the UHMWPE product itself, the surface of the produced UHMWPE product has a uniform structure, and forms a lubricating layer through the surface structure, ensuring a stable ultra-low friction coefficient, the molding process is simple, one-time molding is achieved, the cost is low, and it has a good market prospect.

Description

[Technical Field]

[0001] The present invention relates to the field of polymer physical shaping, and in particular to a method for preparing ultra-high molecular weight polyethylene nanocomposite products. [Background technology]

[0002] With the development of the economy and society, the proliferation of a series of problems caused by friction, such as wear, lubrication, material and energy consumption, has had a major impact on social and economic development and has attracted considerable attention from the scientific and technological community. According to statistics from the World Friction Society, friction losses account for more than one-third of the world's one-time energy losses, resulting in an annual loss of about 1% of gross national product.

[0003] Current market research shows that the main wear-resistant materials commonly used on the market today are ultra-high molecular weight polyethylene, nylon, and polytetrafluoroethylene. UHMWPE generally refers to polyethylene (PE) with a linear structure and a molecular weight of 1.5 million or more, and is a new type of thermoplastic engineering plastic. Polytetrafluoroethylene (PTFE) is a polymer compound made from tetrafluoroethylene through polymerization. Polyamide, commonly known as nylon, is a general term for thermoplastic resins containing repeating amide groups -[NHCO]- on the molecular backbone.

[0004] UHMWPE Performance Characteristics: Ultra-high molecular weight polyethylene (UHMW-PE) is a linear thermoplastic engineering plastic with excellent overall performance. It was first commercialized by Allied Chemical in the United States in 1957, followed by Hoechst in Germany, Hercules Chemical in the United States, and Mitsui Petrochemical in Japan. China first successfully commercialized it in 1964. At the time, the molecular weight of the product was around 1.5 million. However, advances in processing technology have resulted in molecular weights of over 1 million to 9 million. UHMWPE boasts the highest abrasion resistance of any plastic, several times higher than carbon steel and brass and several dozen times higher than regular polyethylene. Its coefficient of friction is close to that of polytetrafluoroethylene (PTFE), lower than other plastics, and lower water absorption than other engineering plastics. It also boasts good anti-adhesion properties, very good impact resistance, high tensile strength, good corrosion resistance, good low-temperature resistance, low density, and low cost.

[0005] Polytetrafluoroethylene (PTFE) performance properties: high chemical stability, good low and high temperature resistance, excellent anti-adhesion properties, very low coefficient of friction, best lubrication properties even for plastics, good insulating properties, excellent ageing resistance and thermal stability, very low water absorption.

[0006] Wear-resistant materials must have good wear resistance and self-lubrication, and must also possess good overall mechanical properties. Compared to polytetrafluoroethylene and nylon, UHMWPE has superior mechanical properties, the best wear resistance, and a friction coefficient comparable to that of polytetrafluoroethylene, demonstrating its comprehensive performance in both wear resistance and lubrication. However, its friction coefficient remains high under lubricated conditions, limiting the application of UHMWPE in lubricated conditions. Therefore, further reduction of the friction coefficient is a key challenge.

[0007] Currently, the primary method for reducing the wear resistance of ultra-high molecular weight polyethylene is blending. Patent CN201710478676.5 discloses an ultra-high molecular weight polyethylene multifunctional nanocomposite suitable for use under water-lubricated conditions. In addition to adding reinforcing fibers to the ultra-high molecular weight polyethylene material, the invention also adds surface-modified tribohydrolyzable nanoparticles. The composite exhibits good wear resistance under water-lubricated conditions. When used in seawater, the boundary film at the friction interface effectively protects the metal bilayer while reducing wear of the polymer composite, thereby reducing metal corrosive wear. While this patent demonstrates good wear resistance under water-lubricated conditions, it is not suitable for use under oil-free lubrication. Therefore, there is a need to develop an UHMWPE product suitable for oil-free lubrication.

[0008] Li Huilin's group at Sichuan University in China (Journal of Friction Science 2004, 24(1):21-24) used compression molding to prepare polypropylene (PP) and MoS2-filled ultra-high molecular weight polyethylene (UHMWPE) composites. They found that adding MoS2 alone improved the wear resistance of UHMWPE, but increased the friction coefficient and reduced mechanical properties. Modifying UHMWPE with PP and MoS2 significantly improved its processing performance. The processing performance, load-carrying capacity, and long-term wear resistance of a 72.7%UHMWPE / 18.2%PP / 9.1%MoS2 ternary composite were significantly superior to those of UHMWPE. UHMWPE primarily exhibited adhesive and fatigue wear. However, the 72.7%UHMWPE / 18.2%PP / 9.1%MoS2 ternary composite underwent only slight plastic deformation when rubbed against steel under the same test conditions. This result significantly improved the wear resistance of UHMWPE while reducing the friction coefficient of UHMWPE products from 0.19 to 0.16. However, this is still far from the friction coefficient of 0.05 to 0.08 under oil lubrication, and further improvement is required. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Chinese Patent Application Publication No. 107338094 [Non-patent literature]

[0010] [Non-Patent Document 1] Journal of Tribology 2004,24(1):21~24 Summary of the Invention [Means for solving the problem]

[0011] In order to solve the above technical problems, the present invention provides a method for preparing an ultra-high molecular weight polyethylene nanocomposite product, the method comprising the steps of: S1: preparing an ultra-high molecular weight polyethylene substrate into an ultra-high molecular weight polyethylene melt and injecting it into a mold; S2: cooling the ultra-high molecular weight polyethylene melt to a first temperature under a preset pressure; S3: injecting a low molecular weight polyolefin nanocomposite melt into the ultra-high molecular weight polyethylene melt at a second temperature; and S4: cooling and molding to prepare the ultra-high molecular weight polyethylene nanocomposite product.

[0012] Preferably, the first temperature is 80 to 100°C, and the second temperature is 90 to 100°C.

[0013] Preferably, the ultra-high molecular weight polyethylene substrate is an ultra-high molecular weight polyethylene powder, and the molecular weight of the ultra-high molecular weight polyethylene substrate is 1 to 9 million g / mol.

[0014] Preferably, the low molecular weight polyolefin nanocomposite melt is a composite product of low molecular weight polyolefin and nanomaterial.

[0015] Preferably, the molecular weight of the low molecular weight polyolefin is 100 to 10,000 g / mol.

[0016] Preferably, the mass fraction of the nanomaterial is 0.1% to 3.0%.

[0017] Preferably, the nanomaterial is a mixture of one or more of graphene, graphite or molybdenum disulfide.

[0018] Preferably, the ultra-high molecular weight polyethylene nanocomposite product is produced by the mold for preparing ultra-high molecular weight polyethylene nanocomposite products provided by the present invention, and in step S1, the ultra-high molecular weight polyethylene melt is injected into the cavity formed by the first mold plate and the movable plate; in step S2, the first mold plate is moved to move the movable plate toward the substrate to maintain the ultra-high molecular weight polyethylene melt at a predetermined pressure; in step S3, the low molecular weight polyolefin nanocomposite melt is injected into the ultra-high molecular weight polyethylene melt at a second temperature, and the first mold plate is retracted at a predetermined speed, the switch is controlled to open the hot runner, and the low molecular weight polyolefin nanocomposite melt is injected; in step S4, the switch is controlled to close the hot runner, followed by cooling and molding.

[0019] Preferably, the preset speed is between 0.1 mm / s and 2 mm / s.

[0020] The present invention further provides a mold for preparing an ultra-high molecular weight polyethylene nanocomposite product, comprising a first mold plate, a second mold plate, and a switch. The second mold plate includes a substrate, a high-pressure spring, a hot runner, and a movable plate. The first mold plate and the movable plate form a cavity for accommodating the ultra-high molecular weight polyethylene melt. The hot runner is fixed to the substrate and is used to inject the low-molecular weight polyolefin nanocomposite melt. The switch is used to control the opening and closing of the hot runner. The movable plate is supported on the substrate via a high-pressure spring and can move horizontally relative to the substrate. The movable plate has through-holes through which the hot runners pass. When the gap between the movable plate and the substrate is minimized, the hot runners protrude from the surface of the movable plate.

[0021] Preferably, the hot runner protrudes from the surface of the movable plate by 1 to 10 mm, and the hot runner has a diameter of 1 to 2 mm.

[0022] Preferably, the total surface area of ​​the hot runners occupies 10% to 60% of the surface area of ​​the movable platen.

[0023] Preferably, the shape of the hot runner is circular or polygonal.

[0024] The present invention further provides an ultra-high molecular weight polyethylene nanocomposite product, which is produced by any one of the above methods for preparing an ultra-high molecular weight polyethylene nanocomposite product.

[0025] Compared with the prior art, the present invention guarantees the mechanical properties and wear resistance of the UHMWPE product itself, the surface of the manufactured UHMWPE product has a uniform structure, and a lubricating layer is formed through the surface structure, ensuring a stable and ultra-low friction coefficient, the molding process is simple, one-time molding is achieved, the cost is low, and it has good market prospects. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a schematic diagram illustrating the preparation method of the ultra-high molecular weight polyethylene nanocomposite product of Example 1. [Figure 2] FIG. 1 is a schematic diagram of a mold for preparing the ultra-high molecular weight polyethylene nanocomposite products of Examples 2 to 9. [Figure 3] FIG. 1 is a schematic diagram showing the steps of the method for preparing the ultra-high molecular weight polyethylene nanocomposite products of Examples 3 to 9. DETAILED DESCRIPTION OF THE INVENTION

[0027] To facilitate understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings, in which preferred embodiments of the present application are shown. However, the present application may be embodied in many different forms and is not limited to the embodiments set forth herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. In this specification, the terms used in the specification of this application are used only for the purpose of describing specific examples and are not intended to limit this application.

[0029] Example 1 As shown in FIG. 1, Example 1 provides a method for preparing an ultra-high molecular weight polyethylene nanocomposite product, the method including: S1: preparing an ultra-high molecular weight polyethylene substrate into an ultra-high molecular weight polyethylene melt and injecting it into a mold; S2: cooling the ultra-high molecular weight polyethylene melt to a first temperature under a preset pressure; S3: injecting a low molecular weight polyolefin nanocomposite melt into the ultra-high molecular weight polyethylene melt at a second temperature; and S4: cooling and molding to prepare the ultra-high molecular weight polyethylene nanocomposite product.

[0030] The first temperature is 80 to 100°C, and the second temperature is 90 to 100°C.

[0031] The ultra-high molecular weight polyethylene substrate is an ultra-high molecular weight polyethylene powder, and the molecular weight of the ultra-high molecular weight polyethylene substrate is 1 to 9 million g / mol. Preferably, the molecular weight is high, and a high molecular weight provides better wear resistance.

[0032] The low-molecular-weight polyolefin nanocomposite melt is a composite product of low-molecular-weight polyolefin and nanomaterials. The molecular weight of the low-molecular-weight polyolefin is 100-10,000 g / mol, and the mass fraction of the nanomaterial is 0.1%-3.0%. The nanomaterial is a mixture of one or more of graphene, graphite, or molybdenum disulfide. The low-molecular-weight polyolefin serves as the base material for room-temperature solid lubricants. Its main function is to maintain the entire lubricant in a solid state and to combine with the UHMWPE product. During wear, it precipitates to form a lubricating film, significantly reducing the friction coefficient. At the same time, it forms a melt at high temperatures, providing wear protection for the product. The amount of nanomaterial added is determined based on the requirements for reducing the friction coefficient of the lubricating layer, improving the heat resistance of the lubricating layer, and achieving wear resistance.

[0033] <Example 2> As shown in FIG. 2, Example 2 provides a mold for preparing an ultra-high molecular weight polyethylene nanocomposite product, which includes: The mold assembly is composed of a first mold plate 1, a second mold plate 2, and a switch 3. The second mold plate 2 includes a substrate 21, a high-pressure spring 22, and a movable plate 23. The first mold plate 1 and the movable plate 23 form a cavity 11 for receiving an ultra-high molecular weight polyethylene melt. The hot runner 24 is fixed to the substrate 21 and is used to inject the low-molecular weight polyolefin nanocomposite melt. The switch 3 is used to control the opening and closing of the hot runner 24. The movable plate 23 is supported on the substrate 21 via the high-pressure spring 22 and moves horizontally relative to the substrate 21. A through-hole is formed in the movable plate 23, through which the hot runner 24 passes. When the gap between the movable plate 23 and the substrate 21 is minimal, the hot runner 24 protrudes from the surface of the movable plate 23 by 1 to 10 mm. When the gap between the movable plate 23 and the substrate 21 is at its maximum, the hot runner 24 does not protrude from the surface of the movable plate 23 .

[0034] The diameter of the hot runner 24 is 1 to 2 mm. The total surface area of ​​the hot runner 24 accounts for 10% to 60% of the surface area of ​​the movable plate 23. The shape of the hot runner 24 is circular or polygonal. The surface area ratio of the hot runner affects the friction coefficient of the final product; a higher ratio results in a lower friction coefficient, but if the ratio is too high, the wear rate of the product decreases. To achieve a comprehensive balance between the friction coefficient and the wear rate, the surface area ratio should be 10 to 60%.

[0035] Example 3 Example 3 provides a more specific example by combining the mold of Example 2 based on the preparation method of Example 1.

[0036] As shown in FIG. 3, this embodiment provides a method for preparing an ultra-high molecular weight polyethylene nanocomposite product, which comprises applying the mold for preparing the ultra-high molecular weight polyethylene nanocomposite product described in Example 2, As shown in FIG. 3a, in step S1, the ultra-high molecular weight polyethylene melt is injected into the cavity 11 formed by the first mold plate 1 and the movable plate 23. In step S2, the first mold plate 1 is moved to move the movable plate 23 toward the substrate 21. After a preset pressure is reached, the movement of the first mold plate 1 is stopped, and the ultra-high molecular weight polyethylene melt is cooled to a first temperature by the action of the high-pressure spring 22 while maintaining the preset pressure.

[0037] As shown in FIG. 3b, in step S3, the low molecular weight polyolefin nanocomposite melt is injected into the ultra-high molecular weight polyethylene melt at a second temperature by retreating the first mold plate 1 at a preset speed, controlling the switch 3 to open the hot runner 24, and injecting the low molecular weight polyolefin nanocomposite melt, the preset speed being 0.1 mm / s to 2 mm / s; If the preset speed is too high, it will affect the pressure retention of the product, so it is preferably less than 2 mm / s. If the retraction speed is low, the pressure will basically not change, flattening the product and simultaneously preventing the injected melt from spilling out of the product surface.

[0038] In step S4, as shown in Figure 3c, the switch 3 is controlled to close the hot runner 24, followed by cooling and molding. After cooling and molding, the mold is opened to remove the ultra-high molecular weight polyethylene nanocomposite product, as shown in Figure 3d.

[0039] The following Examples 4 to 9 provide more specific and illustrative examples that are further based on Examples 1 to 3.

[0040] Example 4 First, an ultra-high molecular weight polyethylene substrate is prepared using melt molding. The molecular weight of the ultra-high molecular weight polyethylene resin is 1 million. After maintaining the pressure (i.e., after reaching the preset pressure), the ultra-high molecular weight polyethylene melt is cooled. After cooling to 80°C, the first mold plate 1 is controllably retreated at a retreat speed of 0.1 mm / s. The movable plate 23 moves following the first mold plate 1 under the action of the high-pressure spring 22. The switch 3 is controlled to open the hot runner 24. During the retreat process, low molecular weight polyolefin composite melt is injected, and the injection temperature is 90-100°C.

[0041] When the gap between the movable platen 23 and the substrate 21 is minimal, the hot runners 24 protrude 1 mm from the surface of the movable platen 23. The hot runners 24 have a diameter of 1 mm and a circular shape, with a total surface area of ​​10% of the surface area of ​​the movable platen 23. The injected low-molecular-weight polyolefin nanocomposite melt is a composite product of low-molecular-weight polyolefin and nanomaterial. The molecular weight of the low-molecular-weight polyolefin is 1000 g / mol, the nanomaterial is graphene, and the mass fraction of the nanomaterial is 0.2%. After final cooling and molding, an ultra-low friction coefficient ultra-high-molecular-weight polyethylene supernanocomposite product is prepared.

[0042] The friction coefficient and mechanical properties of the prepared product were as follows: friction coefficient 0.098, tensile strength 32.3 MPa, and abrasion index 159. The abrasion index is used to characterize the abrasion resistance of UHMWPE products, and the test standard is based on ISO 15527-2007. An exemplary test method involves subjecting the UHMWPE product to mortar abrasion at a rotation speed of 1300 r / min and a water temperature of 5°C, using SLL-4 with a molecular weight of 5 million g / mol as the comparative sample, for abrasion time of 3 hours.

[0043] <Example 5> First, an ultra-high molecular weight polyethylene substrate is prepared using melt molding. The molecular weight of the ultra-high molecular weight polyethylene resin is 3 million. After maintaining the pressure (i.e., after reaching the preset pressure), the ultra-high molecular weight polyethylene melt is cooled. After cooling to 90°C, the first mold plate 1 is controllably retreated at a retreat speed of 1 mm / s. The movable plate 23 moves following the first mold plate 1 under the action of the high-pressure spring 22. The switch 3 is controlled to open the hot runner 24. During the retreat process, low molecular weight polyolefin composite melt is injected, and the injection temperature is 90°C.

[0044] When the gap between the movable platen 23 and the substrate 21 is at its minimum, the hot runners 24 protrude 2 mm from the surface of the movable platen 23. The hot runners 24 have a diameter of 2 mm and a hexagonal shape, with a total surface area of ​​20% of the surface area of ​​the movable platen 23. The injected low-molecular-weight polyolefin nanocomposite melt is a composite product of low-molecular-weight polyolefin and nanomaterial. The molecular weight of the low-molecular-weight polyolefin is 337.58 g / mol, and the nanomaterial is molybdenum disulfide, with a mass fraction of 0.5%. After complete cooling and molding, an ultra-low friction coefficient ultra-high-molecular-weight polyethylene super nanocomposite product is prepared.

[0045] The friction coefficient and mechanical properties of the prepared product are as follows: friction coefficient 0.086, tensile strength 33.6 MPa, wear index 139.

[0046] Example 6 First, an ultra-high molecular weight polyethylene substrate is prepared using melt molding. The molecular weight of the ultra-high molecular weight polyethylene resin is 5 million. After maintaining the pressure (i.e., after reaching the preset pressure), the ultra-high molecular weight polyethylene product melt is cooled. After cooling to 90°C, the first mold plate 1 is controllably retreated at a retreat speed of 2 mm / s. The movable plate 23 moves following the first mold plate 1 under the action of the high-pressure spring 22. The switch 3 is controlled to open the hot runner 24. During the retreat process, low molecular weight polyolefin composite melt is injected, and the injection temperature is 95°C.

[0047] When the gap between the movable platen 23 and the substrate 21 is at its minimum, the hot runners 24 protrude 10 mm from the surface of the movable platen 23. The hot runners 24 have a diameter of 1 mm and a parallelepiped shape. The total surface area of ​​the hot runners 24 accounts for 30% of the surface area of ​​the movable platen 23. The injected low-molecular-weight polyolefin nanocomposite melt is a composite product of low-molecular-weight polyolefin and nanomaterial. The molecular weight of the low-molecular-weight polyolefin is 3000 g / mol, the nanomaterial is graphite, and the mass fraction of the nanomaterial is 0.8%. After complete cooling and molding, an ultra-low friction coefficient ultra-high-molecular-weight polyethylene supernanocomposite product is prepared.

[0048] The friction coefficient and mechanical properties of the prepared product are as follows: friction coefficient 0.080, tensile strength 35.0 MPa, and wear index 115.

[0049] Example 7 First, an ultra-high molecular weight polyethylene substrate is prepared using melt molding. The molecular weight of the ultra-high molecular weight polyethylene resin is 6 million. After maintaining the pressure (i.e., after reaching the preset pressure), the ultra-high molecular weight polyethylene product melt is cooled. After cooling to 100°C, the first mold plate 1 is controllably retreated at a retreat speed of 2 mm / s. The movable plate 23 moves following the first mold plate 1 under the action of the high-pressure spring 22. The switch 3 is controlled to open the hot runner 24. During the retreat process, low molecular weight polyolefin composite melt is injected, and the injection temperature is 100°C.

[0050] When the gap between the movable platen 23 and the substrate 21 is minimal, the hot runners 24 protrude 1 mm from the surface of the movable platen 23. The hot runners 24 have a diameter of 1 mm and a circular shape, with a total surface area of ​​40% of the surface area of ​​the movable platen 23. The injected low-molecular-weight polyolefin nanocomposite melt is a composite product of low-molecular-weight polyolefin and nanomaterial. The molecular weight of the low-molecular-weight polyolefin is 6000 g / mol, the nanomaterial is graphite, and the mass fraction of the nanomaterial is 0.8%. After complete cooling and molding, an ultra-low friction coefficient ultra-high-molecular-weight polyethylene super nanocomposite product is prepared.

[0051] The friction coefficient and mechanical properties of the prepared product are as follows: friction coefficient 0.075, tensile strength 38.9 MPa, wear index 109.

[0052] Example 8 First, an ultra-high molecular weight polyethylene substrate is prepared using melt molding. The molecular weight of the ultra-high molecular weight polyethylene resin is 9 million. After maintaining the pressure (i.e., after reaching the preset pressure), the ultra-high molecular weight polyethylene product melt is cooled. After cooling to 80°C, the first mold plate 1 is controllably retreated at a retreat speed of 0.1 mm / s. The movable plate 23 moves following the first mold plate 1 under the action of the high-pressure spring 22. The switch 3 is controlled to open the hot runner 24. During the retreat process, low molecular weight polyolefin composite melt is injected, and the injection temperature is 90°C.

[0053] When the gap between the movable platen 23 and the substrate 21 is minimal, the hot runners 24 protrude 1 mm from the surface of the movable platen 23. The hot runners 24 have a diameter of 1 mm and a circular shape, with a total surface area of ​​50% of the surface area of ​​the movable platen 23. The injected low-molecular-weight polyolefin nanocomposite melt is a composite product of low-molecular-weight polyolefin and nanomaterial. The molecular weight of the low-molecular-weight polyolefin is 8000 g / mol, the nanomaterial is graphene, and the mass fraction of the nanomaterial is 1.8%. After complete cooling and molding, an ultra-low friction coefficient ultra-high-molecular-weight polyethylene supernanocomposite product is prepared.

[0054] The friction coefficient and mechanical properties of the prepared product are as follows: friction coefficient 0.070, tensile strength 38.6 MPa, and abrasion index 90.

[0055] Example 9 First, an ultra-high molecular weight polyethylene substrate is prepared using melt molding. The molecular weight of the ultra-high molecular weight polyethylene resin is 8 million. After maintaining the pressure (i.e., after reaching the preset pressure), the ultra-high molecular weight polyethylene product melt is cooled. After cooling to 80°C, the first mold plate 1 is controllably retreated at a retreat speed of 1 mm / s. The movable plate 23 moves following the first mold plate 1 under the action of the high-pressure spring 22. The switch 3 is controlled to open the hot runner 24. During the retreating process, low molecular weight polyolefin composite melt is injected, and the injection temperature is 90°C.

[0056] When the gap between the movable platen 23 and the substrate 21 is at its minimum, the hot runners 24 protrude 1 mm from the surface of the movable platen 23. The hot runners 24 have a diameter of 2 mm and a hexagonal shape, with a total surface area of ​​60% of the surface area of ​​the movable platen 23. The injected low-molecular-weight polyolefin nanocomposite melt is a composite product of low-molecular-weight polyolefin and nanomaterial. The molecular weight of the low-molecular-weight polyolefin is 9000 g / mol, and the nanomaterial is molybdenum disulfide, with a mass fraction of 3.0%. After complete cooling and molding, an ultra-low friction coefficient ultra-high-molecular-weight polyethylene super nanocomposite product is prepared.

[0057] The friction coefficient and mechanical properties of the prepared product are as follows: friction coefficient 0.068, tensile strength 38.0 MPa, and abrasion index 98.

[0058] Example 10 Example 10 provides an ultra-high molecular weight polyethylene nanocomposite product, which is produced by the method for preparing an ultra-high molecular weight polyethylene nanocomposite product of Example 1 or Examples 3-9.

[0059] The product can be used to manufacture friction parts that do not require lubrication, such as boot linings for sliding guide shoes in lifts. Prior art technologies require the addition of lubricant between the boot lining and the guide rail to maintain a low coefficient of friction, leading to oil contamination and complicated maintenance. Insufficient lubrication leads to rapid wear of the boot lining, resulting in increased energy consumption and reduced comfort. Boot linings made with this product do not require the addition of lubricant during use, do not generate oil contamination, reduce maintenance complexity, and ensure low energy consumption and high comfort for lift products.

[0060] The product can also be used in other sliding friction parts, such as guide parts of moving platforms, and has a wide range of application value.

[0061] The above description is merely a preferred embodiment of the present invention and does not limit the embodiments and protection scope of the present invention. It should be understood that for those skilled in the art, any form obtained by making equivalent substitutions and obvious modifications based on the contents of the specification and accompanying drawings of the present invention is included within the protection scope of the present invention. [Explanation of symbols]

[0062] 1 first mold plate, 11 cavity, 2 second mold plate, 21 substrate, 22 high-pressure spring, 23 movable plate, 24 hot runner, 3 switch.

Claims

1. S1: preparing an ultra-high molecular weight polyethylene substrate into an ultra-high molecular weight polyethylene melt and injecting it into a mold; S2: Cooling the ultra-high molecular weight polyethylene melt to a first temperature under a preset pressure; S3: Injecting a low molecular weight polyolefin nanocomposite melt into the ultra-high molecular weight polyethylene melt at a second temperature; S4: Cooling and molding to prepare an ultra-high molecular weight polyethylene nanocomposite product; Including, The ultra-high molecular weight polyethylene nanocomposite product comprises: It is composed of a first mold plate, a second mold plate and a switch, the second mold plate includes a substrate, a high-pressure spring, a hot runner, and a movable plate; the first mold plate and the movable plate form a cavity for accommodating the ultra-high molecular weight polyethylene melt; the hot runner is fixed to the substrate, and the hot runner is used to inject the low molecular weight polyolefin nanocomposite melt; the switch is used to control the opening and closing of the hot runner; the movable plate is supported on the substrate via a high-pressure spring and is movable in a horizontal direction relative to the substrate; a through hole is formed in the movable plate, the through hole is used for passing the hot runner, and when the gap between the movable plate and the substrate is minimum, the hot runner protrudes from the surface of the movable plate; Manufactured by applying a mold for preparing ultra-high molecular weight polyethylene nanocomposite products, In step S1, the ultra-high molecular weight polyethylene melt is injected into the cavity formed by the first mold plate and the movable plate; In step S2, the first mold plate is moved to move the movable plate toward the substrate in order to maintain the ultra-high molecular weight polyethylene melt at a predetermined pressure; In step S3, the method of injecting the low molecular weight polyolefin nanocomposite melt into the ultra-high molecular weight polyethylene melt at the second temperature includes: retracting the first mold plate at a preset speed, controlling the switch to open the hot runner, and injecting the low molecular weight polyolefin nanocomposite melt; In step S4, the switch is controlled to close the hot runner, followed by cooling and molding.

2. The first temperature is 80 to 100°C, and the second temperature is 90 to 100°C. The method for preparing an ultra-high molecular weight polyethylene nanocomposite product according to claim 1, characterized in that:

3. The ultra-high molecular weight polyethylene substrate is an ultra-high molecular weight polyethylene powder, and the molecular weight of the ultra-high molecular weight polyethylene substrate is 1,000,000 to 9,000,000 g / mol; The method for preparing an ultra-high molecular weight polyethylene nanocomposite product according to claim 1, characterized in that:

4. The low molecular weight polyolefin nanocomposite melt is a composite product of low molecular weight polyolefin and nanomaterial; The method for preparing an ultra-high molecular weight polyethylene nanocomposite product according to claim 1, characterized in that:

5. The molecular weight of the low molecular weight polyolefin is 100 to 10,000 g / mol; The method for preparing an ultra-high molecular weight polyethylene nanocomposite product according to claim 4, characterized in that:

6. The mass fraction of the nanomaterial is 0.1% to 3.0%; The method for preparing an ultra-high molecular weight polyethylene nanocomposite product according to claim 4, characterized in that:

7. the nanomaterial is a mixture of one or more of graphene, graphite, or molybdenum disulfide; The method for preparing an ultra-high molecular weight polyethylene nanocomposite product according to claim 4, characterized in that:

8. It is composed of a first mold plate, a second mold plate and a switch, the second mold plate includes a substrate, a high-pressure spring, a hot runner, and a movable plate; the first mold plate and the movable plate form a cavity for accommodating ultra-high molecular weight polyethylene melt; The hot runner is fixed to the substrate, and the hot runner is used to inject a low molecular weight polyolefin nanocomposite melt; the switch is used to control the opening and closing of the hot runner; the movable plate is supported on the substrate via a high-pressure spring and is movable in a horizontal direction relative to the substrate; a through hole is formed in the movable plate, the through hole is used for passing the hot runner, and when the gap between the movable plate and the substrate is minimum, the hot runner protrudes from the surface of the movable plate; A mold for preparing an ultra-high molecular weight polyethylene nanocomposite product, characterized in that:

9. The amount of protrusion of the hot runner from the surface of the movable plate is 1 to 10 mm. A mold for preparing the ultra-high molecular weight polyethylene nanocomposite product according to claim 8.

10. The diameter of the hot runner is 1 to 2 mm; A mold for preparing the ultra-high molecular weight polyethylene nanocomposite product according to claim 9.

11. The total surface area of ​​the hot runners accounts for 10% to 60% of the surface area of ​​the movable platen; A mold for preparing the ultra-high molecular weight polyethylene nanocomposite product according to claim 9.

12. The shape of the hot runner is circular or polygonal. A mold for preparing the ultra-high molecular weight polyethylene nanocomposite product according to claim 9.

13. The preset speed is 0.1 mm / s to 2 mm / s. The method for preparing an ultra-high molecular weight polyethylene nanocomposite product according to claim 1, characterized in that:

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